He reached Zhangye, met the King of Gaochang, then received lands of the Western Regions and set up four commanderies, including Xihai. (History of the Northern Dynasties (Beishi), Annals 北史 卷12 大業5年)
He left Linjin Pass, crossed the Yellow River, and at Xiping drilled his troops and had them practice martial arts. (Book of Sui (Suishu), Imperial Annals 隋書 卷003 帝紀 大業5年4月)
When the Tuyuhun king held out at the Fuyuan River, the Interior Secretary Yuan Shou and others divided the army into four columns and surrounded him. (Book of Sui (Suishu), Imperial Annals 隋書 卷003 帝紀 大業5年5月)
Cornered, the Tuyuhun prince Xiantou Wang surrendered, leading some 100,000 men and women. (Book of Sui (Suishu), Imperial Annals 隋書 卷003 帝紀 大業5年5月)
Passing through the Dadoubo Valley, the mountain paths were steep and blizzards scattered the soldiers, most of whom froze to death. (Book of Sui (Suishu), Imperial Annals 隋書 卷003 帝紀 大業5年6月)
Qu Boya, King of Gaochang, came to court, and the Tutun-she of Yiwu presented several thousand li of Western Regions territory. (Book of Sui (Suishu), Imperial Annals 隋書 卷003 帝紀 大業5年6月)